From f106eee10038c2ee5b6056aaf3f6d5229be6dcdd Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Wed, 26 May 2010 14:44:11 -0700 Subject: [PATCH] pids: fix fork_idle() to setup ->pids correctly copy_process(pid => &init_struct_pid) doesn't do attach_pid/etc. It shouldn't, but this means that the idle threads run with the wrong pids copied from the caller's task_struct. In x86 case the caller is either kernel_init() thread or keventd. In particular, this means that after the series of cpu_up/cpu_down an idle thread (which never exits) can run with .pid pointing to nowhere. Change fork_idle() to initialize idle->pids[] correctly. We only set .pid = &init_struct_pid but do not add .node to list, INIT_TASK() does the same for the boot-cpu idle thread (swapper). Signed-off-by: Oleg Nesterov Cc: Cedric Le Goater Cc: Dave Hansen Cc: Eric Biederman Cc: Herbert Poetzl Cc: Mathias Krause Acked-by: Roland McGrath Acked-by: Serge Hallyn Cc: Sukadev Bhattiprolu Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/fork.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/kernel/fork.c b/kernel/fork.c index d32410bd4be7..bf9fef6d1bfe 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1338,6 +1338,16 @@ noinline struct pt_regs * __cpuinit __attribute__((weak)) idle_regs(struct pt_re return regs; } +static inline void init_idle_pids(struct pid_link *links) +{ + enum pid_type type; + + for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type) { + INIT_HLIST_NODE(&links[type].node); /* not really needed */ + links[type].pid = &init_struct_pid; + } +} + struct task_struct * __cpuinit fork_idle(int cpu) { struct task_struct *task; @@ -1345,8 +1355,10 @@ struct task_struct * __cpuinit fork_idle(int cpu) task = copy_process(CLONE_VM, 0, idle_regs(®s), 0, NULL, &init_struct_pid, 0); - if (!IS_ERR(task)) + if (!IS_ERR(task)) { + init_idle_pids(task->pids); init_idle(task, cpu); + } return task; } -- 2.39.2